The present invention relates generally to an automotive diagnostic tool which facilitates data communications between an automobile and diagnostic device, such as a personal computer. More particularly, the present invention relates to electrically isolating the data communications using a Vehicle Communication Interface (VCI) device situated between an automobile's communication diagnostic port and the personal computer. The VCI contains logic circuitry to translate the automobile's On Board Diagnostic (OBD II) signals to an embedded Ethernet controller. Ethernet signals are then non-galvanicly exchanged with an Ethernet to USB controller with an Ethernet transformer. A personal computer is attached via a USB cable to the VCI's Ethernet to USB Controller, permitting information exchange between the automobile and the personal computer.